The present invention relates to a compression ignition internal combustion engine having an auxiliary swirl combustion chamber enabling to reduce noxious components contained in exhaust gas, such as CO, NOx and incombustible hydrocarbon.
In a conventional swirl chamber of a compression ignition chamber, fuel injected from an injection nozzle is mixed with air by forming a strong swirl of air introduced from a primary combustion chamber through a primary communicating passage during the compression stroke of the rising piston. However, the swirling motion causes the so-called thermal pinch phenomenon in which incombustible hydrocarbon and high temperature combustible gas are concentrated on the outer portion and the central portion, respectively, by the centrifugal force of the swirl motion, resulting in the separation therebetween. This results in improper combustion and a consequent increase in harmful components in the exhaust gases.
On the other hand, the diameter of the substantial combustion zone in the swirl chamber is somewhat greater than that of the primary communicating passage between the swirl chamber and the primary combustion chamber. Thus, a vortical combustion is generated in the swirl chamber. The air surrounding the combustion zone, i.e., so called solid rotation zone, is continuously provided to the flame in the central portion of the combustion zone to thereby produce suitable turbulence and to positively introduce fresh air into the combustion zone. As a result, the mixing the fuel and the air is promoted. This is well known to one skilled in the art.